Texas and 10 other states are suing the Obama administration over its directive to U.S. public schools to let transgender students use the bathrooms and locker rooms that match their gender identity.

The lawsuit announced Wednesday includes Oklahoma, Alabama, Wisconsin, West Virginia, Tennessee, Maine, Arizona, Louisiana, Utah and Georgia. It asks a North Texas federal court to declare the directive unlawful in what ranks among the most coordinated and visible legal challenges by states over the socially divisive issue of bathroom rights for transgender persons.

The Obama administration has "conspired to turn workplace and educational settings across the country into laboratories for a massive social experiment, flouting the democratic process, and running roughshod over commonsense policies protecting children and basic privacy rights," the lawsuit reads.

Many of the conservative states involved had previously vowed defiance, calling the guidance a threat to safety while being accused of discrimination by supporters of transgender rights. U.S. Attorney General Loretta Lynch has previously said "there is no room in our schools for discrimination."

The White House had no comment on the lawsuit. The Justice Department said it would review the complaint and did not comment further.

Texas' lieutenant governor has previously said the state is willing to forfeit $10 billion in federal education dollars rather than comply. The directive from the U.S. Justice and Education Departments represents an escalation in the fast-moving dispute over what is becoming the civil rights issue of the day.

Pressed about whether he knew of any instances in which a child's safety had been threatened because of transgender bathroom rights, Republican Texas Attorney General Ken Paxton said "there's not a lot of research" during a news conference about the lawsuit. He said he his office has heard from concerned parents, but didn't say how many, and said he did not meet with any parents of transgender students before drafting the lawsuit.

The states claim that the directive demands "seismic changes" in schools across the U.S. and forces them to let students choose a bathroom "that match their chosen 'gender identity' on any given day."

A timeline of the so-called North Carolina bathroom bill. (News & Observer)

A timeline of the so-called North Carolina bathroom bill. (News & Observer)

Two school districts joined the states in the lawsuit: one is the tiny Harrold school district in North Texas, which has roughly 100 students and passed a policy this week requiring students to use the bathroom based on the gender on their birth certificate. Superintendent David Thweatt said his schools have no transgender students to his knowledge but defended the district taking on the federal government.

"It's not moot because it was thrusted upon us by the federal government," Thweatt said, "or we were going to risk losing our federal funding."

The question of whether federal civil rights law protects transgender people has not been definitively answered by the courts and may ultimately be decided by the Supreme Court. But schools that refuse to comply could be hit with civil rights lawsuits from the government and could face a cutoff of federal aid to education.

The guidance was issued after the Justice Department and North Carolina sued each other overs a state law that requires transgender people to use the public bathroom that corresponds to the sex on their birth certificate. The law applies to schools and many other places.

Supporters say such measures are needed to protect women and children from sexual predators, while the Justice Department and others argue the threat is practically nonexistent and the law discriminatory.

Education officials in Arizona said campuses already had policies to protect students from bullying and discrimination "regardless of their gender identity." A small Arizona school district also joined in the lawsuit.

"The fact that the federal government has yet again decided that it knows what is best for every one of our local communities is insulting and, quite frankly, intolerable," Arizona Superintendent of Public Instruction Diane Douglas said.